Acetylketene o, n-acetals



United States PatentO 3,277,089 ACETYLKETENE 0,N-ACETALS James C.Martin, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester,N.Y., a corporation of New Jersey No Drawing. Filed Oct. 9, 1963, Ser.No. 314,887 4 Claims. (Cl. 260--247.7)

This invention relates to novel chemical compounds and to a method ofpreparing them and more particularly to acetylketene O,N-acetals and totheir preparation by combining a ketene with a ketene O,N-acet-al havingat least one a-hydrogen atom.

The method of the invention and the compounds prepared by it can berepresented by the equation:

The substituents R R and R3 of the ketene and the ketene O,N-acetal,taken singly, can be selected from a board class of monovalentsubstituents including, hydrogen, halogen atoms, and organic radicalshaving up to about 8 carbon atoms that are free of liable hydrogenatoms, e.g., as in amino and hydroxyl groups. These can include, forexample, such monovalent organic radicals as: alkyl and cycloalkyl,particularly lower alkyl, cyclopentyl and cyclohexyl; phenyl and phenylsubstituted with one or more lower alkyl or lower alkoxy radicals;thieny l; alkenyl, particularly lower alkenyl; and carbolkoxy. Takencollectively, R and R of the ketene can also be an alkylene radical thatforms with the carbon to which R and R are attached a 4 to 6 memberedcarbocyclic ring, e.g., as in cyclopentane and cyclohexane. Preferably Rand R are hydrogen, lower alkyl or lower alkylene.

R of the ketene O,N-aeetal is a monovalent hydrocarbon radical free ofnon-aromatic unsaturation and having up to about 6 carbon atoms, such aslower alkyl, cycloalkyl, or phenyl.

The amino substituents R of the ketene O,N-acetal taken singly, aremonovalent hydrocarbon radicals of up to about 8 carbon atoms which arefree of nonaromatic unsaturation, e.g., alkyl, cycloalkyl, phenyl, andlower alkyl-substituted phenyl. Taken collectively, the substituents Rcan be the atoms necessary to complete a heterocyclic ring with thenitrogen atom, e.g., piper-idino, morpholino, thiamorpholino,pyrrolidinyl, etc.

Typical examples of ketenes of the formula, R R C=C=O, that can beemployed in the reaction include ketene, methylketene, ethylketene,n-propylketene, isopropylketene, n-butylketene, isobutylketene,phenylketene, dimethylketene, ethylmethylketene, diethylketene,n-butylethylketene, di-n-propylketene, diisobutylketene,di-n-butylketene, di-nheptylketene, ethyldodecy-lketene,dioctadecylketene, camphoketene, dibenzylketene, ditolylketene,diallylketene, dicarbethoxykeflene, dichloroketene,tetramethyleneketene, pentamethyleneketene, diphenylketene,methylphenylketene, allylmethylketene, methylcarbethoxyketene,ethylcarbethoxyketene, npropylcarbomethoxyketene, and the like.

An important characteristic of the method of the invention is that theketene O,N-acetal must have at least one hydrogen atom on the a-carbonatom. Such ketene O,N-acetals of the formula,

which are suitable for the method of the invention are disclosed byMeerwein et al, Ann. 641, 9 (1961).

3,277,089 Patented Oct. 4, 1966 Ice Examples include:

1-ethoxy-N,N-dimethylvinylamine,

1-( l-methoxyvinyl) piperidine,

1-( l-butoxyvinyDmorpholine, N,N-dibutyl-labutoxyyinylamine, 1ethoxy-N,Ndimethyl-l-prophenylamine,1-ethoxy-N,N-dimethyl-2-phenylvinylamine,l-ethoxy-N,N-diisopropyl-2-phenylvinylamine, 1-ethoxy-N,Ndimethyll-butenylamine, l-ethoxy-N,N-dimethyl-l-decenylamine,1-ethoxy-N-methyLN-phenylvinylamine, etc.

In the practice of the invent-ion, I normally use an equimolar ratio ofketene to ketene O,N-acetal although an excess of acetal is sometimesbeneficial. The reaction can be carried out over a wide range oftemperatures at which the reaction mixture is liquid, e.g., from about-20 C. to 200 C. but temperatures of 25 to 180 C. are preferred.

For the lower members of the series of reactants the reaction is quiteexothermic. Therefore it is usually desirable, though not essential, touse a solvent. An importantcharacteristic of my method is that thereaction is carried out either without a solvent or with a particularclass of solvents, i.e., inert solvents that are either nonpolar or oflow polarity. Specifically, the suitable inert solvents are those havingdielectric constr-ants (e) not greater than 20 when measured at 25 C.and audio frequency, i.e., 20 to 20,000 cycles per second as reported byA. A. Maryott and E. R. Smith in Table of Dielectric Constants of PureLiquids, National Burea of Standards Circular 5414, August 10, 1951. Ihave found that when a highly polar solvent is employed the predominantor sole reaction product is a cyclic compound resulting from the 2:1addition of the ketene and the O N acetal. Such cyclic compounds can beobtained as a minor byproduct of the present method. However, inaccordance with the present invention, the open chain acetylO,N-aceta'ls are obtained as the major product by carrying out thereaction in the absence of a solvent having a dielectric constantgreater than 20 to 25 C. Highest yields of the open chain 1:1 additionproduct of the present invention are obtained with solvents having adielectric constant less than 10 as measured at 25 C.

Examples of suitable non-polar or low polarity solvents for use in themethod of the invention include hydrocarbons such as hexane, benzene,toluene and xylene; chlorinated hydrocarbons such as carbontetrachloride and methylene chloride; and non-polar or low polarityoxygenated compounds such as dioxane, ethyl ether, ethyl acetate, butylether, isobutyl acetate, and the like.

Both reactants can be added simultaneously to the reaction vessel or theketene can be added to the ketene 0,N-acetal. I generally avoid theinverse addition because ketene polymers are sometimes produced when theO,N aoetal is added to the ketene.

The following examples illustrate the preparation of compounds inaccordance with the invention.

Example 1 O CZH5 (CHQzCH-CHzC To a stirred solution of 27.3 g. (0.24mole) of l-ethoxy- N,N-dimethylvinylamine in ml. of benzene undernitrogen was added slowly 21.7 g. (0.31 mole) of dimethylketene. Thereaction was exothermic and the temperature was kept in the range 20 to50 by an ice bath. The reaction solution was distilled through aspinning band column to give 23.5 g. ofl-dimethyla-m-ino-lethoxy-4methyl-1-penten-3-one (I), B.P. 80 (0.5 mm),11 1.5048, together with some of a cycle compound (II) derived from 2molecules of dimethylketene and 1 molecule of1-ethoxyN,N-dimethylvinylamine.

Anal. of (I).-Oalcd. for C I-I NO C, 64.9; H, 10.3; N, 7.6; mol Wt.,185. Found: C, 64.8; H, 10.4; N, 7.3; mol wt. (B.P. in 'benzene), 186.The infrared spectrum of (I). showed strong absorptions at 6.16, 6.5,6.75, 6.85 and 7.0}L. The proton magnetic resonance spectrum (asdetermined on a Varian 40 mo. Model V4300B instrument) showed thefollowing peaks (c.p.s.

relative to. water as an external standard); 18

quartet center at 39 (CH 84 A mixture of 1.26 g. (0.01 mole) ofbutylethylketene and 2.19 g. (0.01 mole) of fi-ethoxy-N,N-diethylstyrylamine is heated at 150 for 4 hr. under nitrogen to give a good yield ofcrude 1-ethoxy-4-ethyl-l-diethylamino-Z- phenyl-1-octen3-one.

Example 4 Under the general conditions of Example 1, the followingketenes and ketene O,N-acetals give the products heptet at 105 (singleproton in isopropyl group); triplet shown:

Ketene Ketene 0,N-Aceta1 Product C4H OCHa C4Ho. O OCH: C=C=O CH2=C CHCH=C C2H5 a)1 C21 5 a):

O C2115 O OCaHI (CeH5)2C=-C=O O4HICH=C CHz-CHz '(C0H5)2CH(% C=C GET-CH1-N (34m N CHr-CHQ CHz-CH:

O CiHu O O C 119 (C5H17)nC=C=O CH2=C (CaH11)2CH CH=C s)2 (CHa):

OHr-CH: O CzHa CHr-OHz O OCaH C C=C=O CHFC CH2 CHI-( CH=C carom NwumCHr-C mom at 144 (CH of ethyl group);.d-oublet at 157 (CH s of isopropylgroup).

0 such a substituted pyrazole from a product of the- The novel compoundsof the invention are useful principally as chemical intermediates. Forexample, they: react with hydrazine to form pyrazoles which have anumber of uses. For example, the pyrazoles can be employed asantioxidant additives for mineral lubricating:

oils in the manner of US. 2,971,912 or as stabilizers for poly(vinylchloride) resins in the manner of U.S. 2,946,765.

The following example illustrates the preparation of invention.

Example 5 0 O 03H; 3)2 H= NHzNH, \N o H A solution of 0.64 g. (0.02mole) of anhydrous hydrazine and 4.54 g. (0.02 mole) of1-ethoxy-4-methyll-morpholino-1-penten-3-one in 20 ml. of ethanol Wasrefluxed for 8 hr. The reaction solution was stripped of low boilersunder vacuum. The viscous residue crystallized slowly and wasrecrystallized from a mixture of hexane and benzene to give 3.1 g. of3-isopropy1-5-morpholino-pyrazole, M.P. 6668.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof, it willbe understood that variations and modifications can be eifected withinthe spirit and scope of the invention as described hereinabove and asdefined in the appended claims.

I claim:

1. A compound of the formula,

wherein R R and R taken singly, are alkyl, cycloalkyl, phenyl, loweralkyl-substituted phenyl, lower alkoxysubstituted phenyl, thienyl,alkenyl and carbalkoxy of up to 8 carbon atoms and, taken collectively,said R and R form a 4 to 6 membered saturated carbocyclic ring with thecommon carbon to which they are attached:

wherein R is alkyl, cycloalkyl or phenyl of up to 6 25 AVROM carbonatoms; wherein the substituents R taken singly, are alkyl, cycloalkyl,phenyl or lower alkyl-substituted phenyl of up to 8 carbon atoms and,taken collectively, represent the atoms necessary to complete aheterocyclic ring selected from the group consisting of piperidino,

. morpholino, thiamorpholino, and pyrrolydinyl.

2. ldimethy1amino-l-ethoxy-4-methyl-1-penten-3-one.

3. 1-ethoxy-4-methyl-l-morpholino-l-penten-S-one.

4. 1 ethoxy 4 ethyl 1 diethylamino 2 phenyl- 1-octen-3-one.

References Cited by the Examiner UNITED STATES PATENTS 7/1964 Martin260294.75

OTHER REFERENCES WALTER A. MODANCE, Examiner.

D. SPEVACK, Assistant Examiner.

1. A COMPOUND OF THE FORMULA,